Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A very stable cell line has been generated that produces monoclonal antibody to VIP designated as CURE.V55. This hybridoma was produced by fusion of spleen cells from an immunized Robertsonian mouse containing the translocated 8.12 chromosome with FOX-NY myeloma cells that are APRT deficient. VIP monoclonal antibody producing cell line #55 was selected by limiting dilutions using thymocytes as feeder layers. Ascites fluid containing high concentration of VIP monoclonal antibody was produced from pristane-primed BALB/c mice. Ascites fluid contained approximately 20 mg/ml IgG and bound 50% of 2 fmol 125I-VIP at a final dilution of 1:50,000. Binding of this IgG1 antibody was inhibited by 50% at 5 nM concentration of either VIP 1-28 or VIP 7-28. Protein-A purified IgG of this antibody, used in a concentration of 30 mg/kg per rat (IV), completely reversed the inhibitory effect of gastric corpus contractions induced by intravenous injection of VIP (10 nmol/kg) in sodium pentothal-anesthetized rats. A control anti-keyhole limpet hemocyanin monoclonal antibody did not alter the stimulatory effect of VIP on gastric corpus contractions. Immunohistochemistry showed that this VIP monoclonal antibody stains neurons, and nerve fibers in human and rat gallbladder and the sphincter of Oddi as previously described with our polyclonal antiserum.
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PMID:Monoclonal antibody to VIP: production, characterization, immunoneutralizing activity, and usefulness in cytochemical staining. 874 93

DtxR is a dimeric, sequence-specific, DNA-binding protein that functions as an iron-dependent, negative global regulator in Corynebacterium diphtheriae. Under high-iron conditions, DtxR represses the synthesis of diphtheria toxin, corynebacterial siderophore, and other components of the high-affinity iron uptake system. Three DtxR-regulated promoter/operators designated tox, IRP1, and IRP2 were reported previously. In this study, we identified and characterized three additional DtxR-regulated promoter/operators from C. diphtheriae designated IRP3, IRP4, and IRP5. When beta-galactosidase was expressed from these three new promoter/ operators in Escherichia coli containing dtxR+ on pDSK29, enzyme levels were 5- to 30-fold lower during high-iron growth than during low-iron growth. In gel shift assays, the mobility of DNA fragments containing each promoter/operator decreased in the presence of purified DtxR and Co2+. In footprinting assays, DtxR protected 36-, 35-, and 30-bp regions of IRP3, IRP4, and IRP5, respectively, from cleavage by DNase I. In the 19-bp core of each promoter/operator, 12 or 13 bp matched the consensus for the DtxR-binding site. The putative polypeptides encoded by the open reading frames (ORFs) downstream from IRP3 and IRP4 were homologous, respectively, to several bacterial transcriptional regulators and to the deduced polypeptide encoded by an ORF located between the E. coli genes for primosomal replication protein N and adenine phosphoribosyltransferase. The putative polypeptide encoded by the ORF downstream from IRP5 was not homologous to any sequence in the protein database at the National Center for Biotechnology Information. When the ORFs downstream from IRP3 and IRP4 were expressed under the control of the phage T7 promoter in E. coli, polypeptide products of the predicted sizes were detected in small amounts by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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PMID:Identification and characterization of three new promoter/operators from Corynebacterium diphtheriae that are regulated by the diphtheria toxin repressor (DtxR) and iron. 931 37

Many reports show that red blood cells of people exposed to lead have a decreased ATP concentration, decreased adenylate energy charge value and many metabolic and morphological abnormalities. Since the synthesis of nucleotides in erythrocytes occurs only through salvage pathways, we hypothesized that a decrease in nucleotide concentrations may be caused by lead-induced inhibition of erythrocyte phosphoribosyltransferases: adenine APRT (EC 2.4.2.7) and hypoxanthine-guanine HPRT (EC 2.4.2.8). These enzymes enable the reutilization of purine bases (adenine, guanine, hypoxanthine) converting them to mononucleotides (AMP, GMP, IMP), substrates for the synthesis of high-energy nucleotides. To confirm the hypothesis two experiments were performed: (i) in vitro, using a lysate of human erythrocytes incubated (5, 10, 30min) with lead ions (100microM, 10microM, 1microM, 500nM, 100nM lead acetate) and 100microM sodium acetate for the control, (ii) in vivo, using a lysate of rat erythrocytes taken from rats chronically exposed to lead (0.1% lead acetate in drinking water for 9 months, resulting in whole blood lead concentration 7microg/dL). The activities of APRT and HPRT were determined using HPLC method, which allowed concurrent determination of the activity of both enzymes in erythrocyte lysates. We have shown that, lead ions: (i) moderately inhibit both phosphoribosyltransferases in erythrocytes, this influence being detectable even at very low concentrations (ii) participate in hemolysis, the intensity of which negatively correlates with the activity of phosphoribosyltransferases. Our results indicate the necessity of further research on the role of lead-induced APRT and HPRT inhibition as one of the mechanisms of lead toxicity.
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PMID:Inhibition of erythrocyte phosphoribosyltransferases (APRT and HPRT) by Pb2+: a potential mechanism of lead toxicity. 1942 46


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